Air bag in use for head protection air bag device

ABSTRACT

An air bag is stored in the upper fringe of the openings on the cabin-inside side, while being folded. The air bag includes a gas inflow part for flowing inflation gas into the air bag, and a main body which inflates when receiving the inflation gas. The main body includes front- and rear-seat inflation chambers, and a gas passage extending forward from the gas inflow part and allowing the inflation gas to flow from inflow ports opened in the upper parts of the front-and rear-seat inflation chambers to the front- and rear-seat inflation chambers per se. The inflow port of the rear-seat inflation chamber is opened in a direction substantially orthogonal to an axial direction of the gas passage. A front-side peripheral edge is disposed to be higher than a rear-side peripheral edge.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an air bag in use for a headprotection air bag device. More particularly, the invention relates toan air bag which, while being folded, is stored in the upper fringe ofthe openings on the cabin-inside side, and develops and inflates tocover the openings when receiving the inflation gas, and includes front-and rear-seat inflation chambers located at positions near the sides offront and rear seats.

[0003] The present application is based on Japanese Patent ApplicationNo. 2000-232201, which is incorporated herein by reference.

[0004] 2. Description of the Related Art

[0005] A conventional head protection air bag device is constructed withan air bag and an inflator of the cylinder type for supplying inflationgas to the air bag (DE 29806200 Ul and GB 2324068, and the like).

[0006] The air bag, while being folded, is stored in the upper fringe ofthe openings on the cabin-inside side, and develops and inflates tocover the openings when receiving the inflation gas, and includes front-and rear-seat inflation chambers respectively located at positions nearthe sides of front and rear seats.

[0007] The air bag includes a gas inflow part which is located at therear upper part and coupled to an inflator so as to flow inflation gasfrom the rear side into the air bag per se, and a main body including afront-seat inflation chamber and a rear-seat inflation chamber, anddevelops and inflates to cover the openings when receiving the inflationgas.

[0008] In addition to the front- and rear-seat inflation chambers, theair bag further includes a gas passage extending forward from the gasinflow part and being disposed above the front- and rear-seat inflationchambers and allowing the inflation gas to flow from inflow ports openedin the upper parts of the front- and rear-seat inflation chambers to thefront- and rear-seat inflation chambers per se.

[0009] In the conventional head protection air bag device, the gaspassage is extended forward from the gas inflow part linearly andsubstantially horizontally.

[0010] With this, the gas passage is filled, to a certain extent, withinflation gas over its entire length, and then the inflation gas flowsinto the front- and rear-seat inflation chambers via inflow portsassociated therewith. There is room for improvement in quickly start thedeveloping and inflating of the folded front- and rear-seat inflationchambers below.

[0011] In particular above the rear-seat inflation chamber, theinflation gas flowing forward through the gas passage is strong.Accordingly, in the initial stage of the passage of the inflation gas,inflation gas sometimes is hard to flow into the rear-side peripheraledge. Accordingly, there is room for improvement in securing a quickstart of the downward developing/inflating operation.

[0012] A possible measure taken for this is to change the gas flowingpassage so as to end the developing/inflating operation of the rear-seatinflation chamber and to develop and inflate the front-seat inflationchamber. This measure, however, further delays the ending of thedeveloping/inflating operation of the front-seat inflation chamber whichis likely to delay its developing/inflating operation, because thefront-seat inflation chamber is remote from the gas inflow part.

SUMMARY OF THE INVENTION

[0013] Accordingly, an object of the present invention is to provide anair bag in use for a head protection air bag device which lessens adelay of the ending of a developing/inflating operation of a front-seatinflation chamber, and quickly starts a developing/inflating operationof a rear-seat inflation chamber.

[0014] To achieve the above object, there is provided an air bag in usefor a head protection air bag device in which the air bag, while beingfolded, is stored in the upper fringe of the openings on thecabin-inside side, and includes a gas inflow part, located at the rearupper part, for flowing inflation gas into the air bag and a main bodywhich develops and inflates to cover the openings when receiving theinflation gas, the main body including front- and rear-seat inflationchambers, located at positions near the sides of front and rear seats,for receiving inflation gas, and a gas passage extending forward fromthe gas inflow part and being disposed above the front- and rear-seatinflation chambers and allowing the inflation gas to flow from inflowports opened in the upper parts of the front- and rear-seat inflationchambers to the front- and rear-seat inflation chambers per se. The airbag is improved such that the inflow port of the rear-seat inflationchamber is opened in a direction substantially orthogonal to an axialdirection of the gas passage, and a front-side peripheral edge isdisposed to be higher than a rear-side peripheral edge.

[0015] The air bag thus constructed may have such a preferableconstruction that a plurality of inflow ports of the front-seatinflation chamber are opened in a direction substantially orthogonal toan axial direction of the gas passage, while being arrayed along the gaspassage, and a guide is formed on the peripheral wall of the gas passagelocated above the plurality of inflow ports for the front-seat inflationchamber, and directs downward part of the inflation gas flowing forwardand guides the inflation gas from the inflow port of the rear-seatinflation chamber into the front-seat inflation chamber.

[0016] In the air bag thus constructed, inflation gas flows from the gasinflow part into the main body. Then, the inflation gas passes throughthe gas passage extending forward and flows forward. As recalled, theinflow port of the rear-seat inflation chamber is opened in a directionsubstantially orthogonal to an axial direction of the gas passage, and afront-side peripheral edge is disposed to be higher than a rear-sideperipheral edge. Accordingly, the front-side peripheral edge of theinflow port is easy to interfere with the inflation gas by an extentcorresponding to the dimension by which the front-side peripheral edgeis higher than the rear-side peripheral edge. The front-side peripheraledge directs the inflation gas resulting from the interference to therear-seat inflation chamber. This leads to a quick start of thedeveloping/inflating operation of the rear-seat inflation chamber.

[0017] The inflow port of the rear-seat inflation chamber has merelysuch a configuration that it is opened in the direction substantiallyorthogonal to the axial direction of the gas passage, and its front-sideperipheral edge is higher than its rear-side peripheral edge. Such aconfiguration of the inflow port cannot direct the entire inflation gasflowing forward within the gas passage to the rear-seat inflationchamber, as a matter of course. Therefore, a delay of the ending of thedeveloping/inflating operation of the front-seat inflation chamber maybe minimized by appropriately adjusting a height of the front-sideperipheral edge from the rear-side peripheral edge.

[0018] Accordingly, the air bag of the embodiment which is used for thehead protection air bag device is capable of minimizing the delay of theending of the developing/inflating operation of the front-seat inflationchamber, and quickly starts the developing/inflating operation of therear-seat inflation chamber.

[0019] Where the air bag has the preferable construction as statedabove, the developing/inflating operation of the front-seat inflationchamber is also quickly started.

[0020] The inflation gas flows forward through the rear passage abovethe front-seat inflation chamber and flows to the upper part of thefront-seat inflation chamber. As recalled, the guide is formed on theperipheral wall of the gas passage located above the plurality of inflowports for the front-seat inflation chamber. Therefore, part of theinflation gas flowing forward is directed downward by the guide, andguided into the front-seat inflation chamber, from the inflow port onthe rear side. As a result, the developing/inflating operation of thefront-seat inflation chamber is quickly started.

[0021] Also in this case, the inflation gas may smoothly be introducedfrom the inflow ports into the front-seat inflation chamber on the frontside of the inflow port by appropriately adjusting the downwardprojection quantity of the guide, as a matter of course. As a result,the front-seat inflation chamber being folded is developed downward fromthe substantially entire region as viewed in the front/rear direction.This leads to quicken the ending of the developing/inflating operationof the front-seat inflation chamber.

[0022] Features and advantages of the invention will be evident from thefollowing detailed description of the preferred embodiments described inconjunction with the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In the accompanying drawings:

[0024]FIG. 1 is a front view showing a head protection air bag deviceinto which an air bag forming an embodiment of the present invention isincorporated, the view being taken from the cabin inside;

[0025]FIG. 2 is an enlarged, longitudinal sectional view taken on lineII-II in FIG. 1;

[0026]FIG. 3 is a front view showing an air bag being developed flatwhich is the embodiment;

[0027]FIG. 4 is an enlarged, partial front view showing the rear endpart of the air bag being developed flat;

[0028]FIG. 5 is an enlarged, partial transverse cross sectional viewshowing the air bag being inflated, the view showing an area of the airbag taken on line V-V in FIG. 4;

[0029]FIG. 6 is an enlarged, partial front view showing the front endpart of the air bag being developed flat; and

[0030]FIG. 7 is a partial, front view showing an air bag which isanother embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] An embodiment of the present invention will be described withreference to the accompanying drawings.

[0032] An air bag 11 of the embodiment is used for a head protection airbag device M. The air bag cover 11, while being folded, is stored in aregion including the lower fringe of a front pillar FP, the lower fringeof the roof side rail RR, and the upper side of a rear pillar RP, asshown in FIG. 1.

[0033] The head protection air bag device M is made up of an air bag 11,an inflator 51, mounting brackets 46 to 48, 52, and an air bag cover 9.

[0034] The inflator 51, as shown in FIG. 1, takes the form of a cylinderwhich supplies gas for inflation to the folded air bag 11. Gas-inflowparts 13 to be given later are attached to the air bag 11.

[0035] The mounting bracket 52 is formed with a metal sheet, and holdsdown from the outer peripheral side the inflator 51 to which thegas-inflow parts 13 (to be described later) of the air bag 11 areattached, for each gas-inflow part 13. The mounting bracket is mountedon a sheet metal inner panel 2 of a vehicle body 1 on the indoor side ofthe rear pillar RP.

[0036] As shown in FIGS. 1 and 2, the mounting bracket 46 formed with ametal sheet sandwiches two mounting parts 12 to be described later. Themounting bracket 46 includes an inner plate 46 a on the cabin inside INand an outer plate 46 b on the cabin outside OU. Mount holes 46 c arethrough formed in those inner and outer plates 46 a and 46 b, whilecorresponding to a mounting hole of each mounting part 12. The mountingparts 12 are mounted on the inner panel 2 in a manner that mount bolts49 are inserted into mount holes 12 a and 46 c, and screwed into a nut 2b fastened to the circumferential edge of a mount hole 2 a of the innerpanel 2.

[0037] As shown in FIG. 1, the mounting bracket 47 formed with a metalsheet sandwiches a mounting part 12, which is located at a mid positionof the air bag 11 as viewed in the front/rear direction. It includes aninner plate 47 a that is located on the cabin inside like the innerplate 46 a of the mounting bracket 46, and an outer plate 47 b locatedon the cabin outside. The outer plate 47 b supports a cabin-outsidesurface and a lower surface of the folded air bag 11, and is shaped likeL in cross section so as to prevent it from entering the cabin outsideof a garnish 6 of the rear pillar RP when the air bag 11 is developedand inflated. Mount holes (not attached with reference numeral) throughwhich a mount bolt 49 will be inserted are formed in the inner and outerplates 47 a and 47 b at a position corresponding to the mount hole 12 aof the mounting part 12.

[0038] As shown in FIG. 1, the mounting bracket 48 formed with a metalsheet sandwiches two mounting parts 12, which are located at a rearposition of the air bag 11. It includes two inner plates 48 a that arelocated on the cabin inside like the inner plate 46 a of the mountingbracket 46, and one outer plate 48 b located on the cabin outside of thetwo inner plates 48 a. The outer plate 48 b also supports acabin-outside surface and a lower surface of the folded air bag 11 likethe outer plate 47 b of the mounting bracket 47. And, it is shaped likeL in cross section so as to prevent it from entering the cabin outsideof the garnish 6 of the rear pillar RP when the air bag 11 is developedand inflated. Mount holes (not attached with reference numeral) throughwhich a mount bolt 49 will be inserted are formed also in the inner andouter plates 48 a and 48 b at a position corresponding to the mount hole12 a of the mounting part 12.

[0039] The air bag cover 9, as shown in FIGS. 1 and 2, is defined by thelower fringes of a pillar garnish 4 located on the front pillar FP and alower fringe of a roof head lining 5 located on the roof side rail RR.The pillar garnish 4 and the roof head lining 5 are made of syntheticresin, and are secured to the inner panel 2 of the vehicle body 1, whichis located on the indoor side of the front pillar FP and the roof siderail RR.

[0040] The air bag 11 is hollow woven by using polyamide and polyesterthreads. As shown in FIGS. 1 and 3, the air bag 15, as shown in FIGS. 1and 3, includes a main body 14, a gas inflow part 13, and a plurality ofmounting parts 12. The main body 14 receives gas for inflation from theinflator 51, and develops the folded air bag into an inflated one tocover the opening W. The gas-inflow parts 13 introduces the inflationgas from the inflator 51 to the main body 14. The mounting parts 12 areprovided on the upper edge 11 a of the main body 14.

[0041] The gas inflow part 13 is disposed to project to the rear end ofthe main body 14, and is cylindrical in shape so that it may be appliedto the inflator 51.

[0042] The plurality of mounting parts 12 are disposed projecting abovea peripheral edge part 34 on the upper edge 11 a side of the main body14 and a plate-like member 42, which will be described later. Themounting brackets 46, 47 and 48 used for the mount on the inner panel 2are secured to the mounting parts 12. The mount holes 12 a through whichthe mount bolt 49 will be inserted are formed in the mounting parts 12.

[0043] The main body 14 is constructed with an inflating section 15which communicates with the gas-inflow parts 13, receives the inflationgas, and inflates to separate a cabin-inside side wall 15 a (see FIGS.3, 4, 5) from a cabin-outside side wall 15 b, and a non-inflatingsection 33 which rejects the incoming gas for inflation.

[0044] The inflating section 15 is constructed with a rear-seatinflation chamber 16, a front-seat inflation chamber 21, and a gaspassage 27. The rear-seat inflation chamber 16 may be arranged on theside positions of the rear seat of the vehicle when the air bag isdeveloped and inflated. The front-seat inflation chamber 21 may bearranged on the side positions of the front seat when the air bag isdeveloped and inflated. The gas passage 27 extends forwardly from thegas inflow part 13, and disposed above the front- and rear-seatinflation chambers 21 and 16, and allows inflation gas to flow into thefront- and rear-seat inflation chambers. The gas passage 27 includes arear passage 28, a front passage 29, and an intermediate passage 30. Therear passage 28 is disposed above the rear-seat inflation chamber 16.The front passage 29 is disposed above the front-seat inflation chamber21. The intermediate passage 30 intercommunicates the rear passage 28and the front passage 29 above a rectangular plate portion 42 b to bedescribed later.

[0045] The non-inflating section 33 is constructed coupling thecabin-inside side wall 15 a and the cabin-outside side wall 15 b. In theembodiment, it is constructed with the peripheral edge part 34, couplingparts 36 to 40, and a plate-like member 42. The peripheral edge part 34surrounds the inflating section 15. Further, it includes a partitioningpart 34 a parting the space into the gas-inflow part 13 and therear-seat inflation section 16.

[0046] The plate-like member 42 includes a triangular plate portion 42 aprovided on the front side of the main body 14, and a rectangular plateportion 40 b provided under the intermediate passage 30 between thefront and rear seat inflation parts 21 and 16. The plate-like member 42defines an overall configuration of the main body 14 ranging from thegas-inflow parts 13 to the front end of the main body 14. Further, itreduces a time taken till the inflating operation ends.

[0047] The peripheral edge part 34 and the thickness defining members 36to 40, together with the mounting parts 12, are woven more densely thanthe plate-like member 42. The plate-like member 42 is coarsely wovenbecause it is not located at the boundary of the inflating section 15and hence there is no need of taking any measure for preventing theinflation gas from leaking. It is coarsely woven in two clothes, andthose clothes are bonded together in a spot bonding manner. In theembodiment, such structural portions as the triangular plate portion 42a and the rectangular plate portion 42 b are disposed in the vicinity ofthe mounting parts 12 on the upper edge 11 a side and the gas inflowpart 13, and under the peripheral edge part 34 right under the rear-seatinflation chamber 16 and the front-seat inflation chamber 21 of anair-bag lower fringe 11 b.

[0048] The coupling parts 36 to 38 are shaped like T or J whilevertically extending within a region of the front-seat inflation section21. Those parts are arranged side by side as viewed in the longitudinaldirection of the vehicle, while being separated from the peripheral edgepart 34. The coupling parts 39 and 40, shaped like I, extend downwardfrom the partitioning part 34 a of the peripheral edge part 34 into aregion of the rear-seat inflation section 16, while being arranged sideby side as viewed in the longitudinal direction.

[0049] Those thickness defining members 36 to 40 are provided for makingeven the thickness of the front and back seat inflation parts 21 and 16when the inflation gas flows into the inflating section 15 to inflateit. Further, those parts cause a structure ranging from a position nearthe gas-inflow parts 13 to the front part of the main body 14 to exhibita tension. With this, even if such a pressing force as to press the mainbody 14 out of the vehicle acts on the main body 14, the main body 14 isimmovable.

[0050] A plurality (four in the embodiment) of inflow ports 22 to 25 areformed in the front-seat inflation chamber 21. Those inflow ports allowinflation gas to flow from the front passage 29 of the gas passage 27into the front-seat inflation chamber with the aid of the coupling parts36 to 38. The inflow port 22 is opened at a position above and betweenthe peripheral edge part 34 of the front end of the front-seat inflationchamber 21 and the coupling part 36. The inflow port 23 is opened aboveand between the coupling parts 36 and 37. The inflow port 24 is openedabove and between the coupling parts 37 and 38. The inflow port 25 isopened above and between the coupling part 38 and the peripheral edgepart 34 of the front-seat inflation chamber 21. Those inflow ports 22 to25 are arranged such that the axial direction of those inflow ports arevertical and substantially orthogonal to an axial direction X2 (seeFIGS. 3 and 6) of the front passage 29 of the gas passage 27, which isdisposed in the front/rear direction (substantially horizontal).

[0051] In the embodiment, the inflow port 25 located at the rear end ofthe front-seat inflation chamber 21 is located at the position of acenter pillar CP when the air bag 11 is mounted on the vehicle.

[0052] One inflow port 17 is bored in the upper part of the front sideof the rear-seat inflation chamber 16. The inflow port 17 allowsinflation gas to flow from the rear passage 28 of the gas passage 27 tothe rear-seat inflation chamber. The axial direction of the opening ofthe inflow port 17 is vertical and substantially orthogonal to the axialdirection X1 (FIGS. 3 and 4) of the rear passage 28 of the gas passage27, which is disposed in the front/rear direction (substantiallyhorizontal).

[0053] The front-side peripheral edge 18 of the inflow port 17 of therear-seat inflation chamber 16, as shown in FIG. 4, is higher than therear-side peripheral edge 19 by a dimension of H1 (20 mm in theembodiment) in a state that the air bag 11 is developed flat.

[0054] The peripheral edge 18 of the peripheral edge of the inflow port17 is positioned at the uppermost position of the peripheral edge part34 which defines the front end of the rear-seat inflation chamber 16,and in the embodiment, it is on the same level with a beginning part 34b of the partitioning part 34 a, which is closer to the gas inflow part13. The rear-side peripheral edge 19 of the peripheral edge of theinflow port 17 is positioned at the fore end of a linear part 34 c ofthe partitioning part 34 a, which linearly slants downward from thebeginning part 34 b. In this embodiment, the peripheral wall of the rearpassage 28 (an upper edge 34 d of the peripheral edge) is linearly andhorizontally extended. The partitioning part 34 a forming the peripheralwall on the lower edge side of the rear passage 28 is configured suchthat the linear intermediate part 34 c is extended obliquely anddownward, and the rear passage 28 is expanded in diameter toward thefront side. Accordingly, the front-side peripheral edge 18 is higherthan the rear-side peripheral edge 19 by the dimension H1.

[0055] In the embodiment, as shown FIGS. 3 and 6, above the inflow port25 on the rear side of the front-seat inflation chamber 21, a guide 31is formed on the peripheral wall on the upper edge side of the frontpassage 29 of the gas passage 27. The guide 31 is configured such thatthe peripheral edge part 34 is gently inclined downward from theintermediate passage 30. The guide 31 is provided to positively directdownward part of the inflation gas flowing forward within theintermediate passage 30 and guide the gas from the inflow port 25 to thefront-seat inflation chamber 21.

[0056] In the embodiment, a downward projection quantity H2 between thelower end 31 a of the guide 31 and the peripheral wall of theintermediate passage 30 on the upper edge side is set at 30 mm.

[0057] The intermediate passage 30 is configured such that the lowerperipheral wall is slanted downward more sharply than the guide 31 so asto increase its diameter to the front. In other words, the front end ofa mid position 34 e on the upper side of the rectangular plate portion42 b of the peripheral edge part 34, is greatly bent downward.

[0058] In the embodiment, as indicated by a two-dot chain line in FIG.3, folding of the air bag is repeated in opposite directions and holdingedges C are formed at the crests and troughs, whereby the air bag isformed like bellows acting so as to move the lower edge of the 11 b tothe upper edge 11 a. In manufacturing the air bag 11, a base cloth iswoven to have a predetermined pattern. Then, if required, it isprocessed to increase its heat resistance, and is coated with siliconeor the like to form a coating layer thereon in order to prevent theinflation gas from being leaked. Incidentally, after the base cloth iswoven, the coating layer is formed over the outer surface of the basecloth because it is impossible to coat its inner surface with coatingmaterial.

[0059] After folded, the air bag is wrapped with a tape 44 which may bebroken (FIGS. 1 and 2), in order to prevent its re-expansion. Then, theinflator 51 and the mounting brackets 46 to 48, and 52 are mounted onit, whereby an air bag assembly is formed. A tape 44 which may bebroken, is further applied to the areas of the mounting brackets 47 and48 so as to prevent those mounting brackets 47 and 48 from separatingfrom the air bag 11.

[0060] The mounting brackets 46 to 48, and 52 are located atpredetermined positions of the inner panel 2; The mount holes 12 a orthe like are passed therethrough and fastened by bolts 49 and 53; andthe mounting brackets 46 to 48; and 52 are fastened to the inner panel2, whereby the air bag assembly is mounted to the vehicle body 1.Thereafter, the pillar garnish 4 and the roof head lining 5 are attachedto the vehicle body 1. Further, a rear pillar garnish 6 and a centerpillar garnish 7 are attached to the vehicle body 1. Here, the air bag11, together with the head protection air bag device M, has been mountedon the vehicle.

[0061] The head protection air bag device M is mounted on the vehicle,and the inflator 51 is operated. An inflation gas G output from theinflator 51 flows from the gas-inflow parts 13 and through the gaspassage 27, i.e., the rear passage 28, the intermediate passage 30 andthe front passage 29 in this order. The gas flows out of the inflowports 22 to 25 in the form of branch streams G1 to G4 of the gas, andreaches the front-seat inflation chamber 21. A branch stream G5 of thegas flows out of the inflow port 17 and into the rear-seat inflationchamber 16. The inflating section 15 starts to inflate while bringingout of its folded state. The air bag 11 breaks the tape 44 with whichthe air bag is wrapped; forcibly opens the pillar garnish 4 and the airbag cover 9 on the lower edge side of the roof head lining 5; andgreatly inflates so as to cover the opening W and the cabin-inside sideof the rear pillar RP, while projecting downward.

[0062] In the embodiment, the inflow port 17 of the rear-seat inflationchamber 16 is opened to the gas passage 27 of the air bag 11 in thedirection substantially orthogonal to the axial direction X1 of the gaspassage 27 (rear passage 28), which is disposed in the front/reardirection. The front-side peripheral edge 18 of the inflow port is lowerthan the rear-side peripheral edge 19 by the dimension H1. Accordingly,the front-side peripheral edge 18 of the inflow port 17 is easy tointerfere with the inflation gas G by an extent corresponding to thedimension H1 by which the front-side peripheral edge 18 is higher thanthe rear-side peripheral edge 19. The front-side peripheral edge directsthe inflation gas G5 resulting from the interference to the rear-seatinflation chamber 16. This leads to a quick start of thedeveloping/inflating operation of the rear-seat inflation chamber 16.

[0063] The inflow port 17 of the rear-seat inflation chamber 16 hasmerely such a configuration that it is opened in the directionsubstantially orthogonal to the axial direction X1 of the gas passage 27(rear passage 28), and its front-side peripheral edge 18 is higher thanits rear-side peripheral edge 19. Such a configuration of the inflowport cannot direct the entire inflation gas G flowing forward within thegas passage 27 to the rear-seat inflation chamber 16, as a matter ofcourse. Therefore, a delay of the ending of the developing/inflatingoperation of the front-seat inflation chamber 21 may be minimized byappropriately adjusting a height of the front-side peripheral edge 18from the rear-side peripheral edge 19.

[0064] Accordingly, the air bag 11 of the embodiment which is used forthe head protection air bag device M is capable of minimizing the delayof the ending of the developing/inflating operation of the front-seatinflation chamber 21, and quickly starting the developing/inflatingoperation of the rear-seat inflation chamber 16.

[0065] The dimension H1 of the front-side peripheral edge 18 of theperipheral edge of the inflow port 17 of the rear-seat inflation chamber16 from the rear-side peripheral edge 19 is preferably 15 to 40% of thedimension B1 of the opening of a general portion 28 a (front-sideperipheral edge 18 or beginning part 34 b) of the rear passage 28 in astate that the air bag 11 developed flat. If the height H1 is smallerthan 15%, the effect of securing the quick start of thedeveloping/inflating operation of the rear-seat inflation chamber 16 islessened. If it is in excess of 40%, its interference with the inflationgas G flowing to the front-seat inflation chamber 21 is large. As aresult, there is a danger of delaying the ending of thedeveloping/inflating operation of the front-seat inflation chamber 21.

[0066] In the air bag 11 of the embodiment, the front-seat inflationchamber 21 is opened in the direction substantially orthogonal to theaxial direction X2 of the gas passage 27 (front passage 29). A pluralityof inflow ports 22 to 25 are arrayed along the front passage 29 of thegas passage 27. Provided above the inflow port 25 on the rear side isthe guide 31 for directing downward part G4 of the inflation gas Gflowing forward and guiding the gas from the inflow port 25 on the rearside into the front-seat inflation chamber 21.

[0067] The inflation gas G flows forward through the rear passage 28above the front-seat inflation chamber 21 and to the front side of theintermediate passage 30. When the inflation gas G flows to the upperpart of the front-seat inflation chamber 21, part G4 of the inflationgas G flowing forward is directed downward by the guide 31, and guidedinto the front-seat inflation chamber 21, from the inflow port 25 on therear side. As a result, the developing/inflating operation of thefront-seat inflation chamber 21 is quickly started.

[0068] Also in this case, the inflation gases G1 to G3 may smoothly beintroduced from the inflow ports 22 to 24 into the front-seat inflationchamber 21 on the front side of the inflow port 25 by appropriatelyadjusting the downward projection quantity H2 of the guide 31, as amatter of course. As a result, the front-seat inflation chamber 21 beingfolded is developed downward from the substantially entire region asviewed in the front/rear direction. This leads to quicken the ending ofthe developing/inflating operation of the front-seat inflation chamber21.

[0069] The quantity H2 of the downward projection of the lower end 31 aof the guide 31 from the intermediate passage 30 is preferably 20 to 50%of the opening dimension B2 of a general portion 29 a (portion of theupper end of the coupling parts 36 to 38) of the front passage 29. If itis smaller than 20%, the effect of securing the quick start of thedeveloping/inflating operation of the rear-seat inflation chamber 16 isless effected. If it is in excess of 50%, its interference with theinflation gas G flowing to the front side of the front-seat inflationchamber 21 is large. As a result, there is a danger of delaying theending of the developing/inflating operation of the front-seat inflationchamber 21.

[0070] In the above-mentioned embodiment, the inflow port 17 of therear-seat inflation chamber 16 is located on the front side thereof. Ifrequired, the inflow port 17 may be located on the rear side of therear-seat inflation chamber 16 as shown in FIG. 7. Also in this case,the front-side peripheral edge 18 of the peripheral edge of the openingof the inflow port 17 is selected to be higher than the rear-sideperipheral edge 19 by the height H1.

[0071] In the embodiment mentioned above, the coupling parts 39 and 40of the rear-seat inflation chamber 16 are linearly and verticallyextended. In an alternative, those coupling parts 39 and 40 may beextended vertically while being curved, as shown in FIG. 7. The samething is true for the coupling parts 36 to 38 within the front-seatinflation chamber 21.

[0072] In the embodiment, a hollow weave air bag is used for the air bag15. The air bag may be formed by stitching, adhering using adhesive,welding using high frequency welder or another suitable process. In thiscase, the invention may be applied to the configuration of theperipheral edge of the inflow port.

[0073] Although the invention has been described in its preferred formwith a certain degree of particularity, it is understood that thepresent disclosure of the preferred form can be changed in the detailsof construction and in the combination and arrangement of parts withoutdeparting from the spirit and the scope of the invention as hereinafterclaimed.

What is claimed is:
 1. An air bag in use for a head protection air bagdevice in which said air bag, while being folded, is stored in an upperfringe of openings on a cabin-inside side of a vehicle, said air bagcomprising: a gas inflow part for flowing inflation gas; a gas passageextending forward from said gas inflow part; a front-seat inflationchamber located at a position near a side of a front seat for receivingthe inflation gas; and a rear-seat inflation chamber located at aposition near a sides of a rear seat for receiving the inflation gas,said front- and rear-seat inflation chambers being disposed below saidgas passage through respective inflow ports formed in upper parts ofsaid front- and rear-seat inflation chambers to allow the inflation gasto flow into said front- and rear-seat inflation chambers; wherein saidinflow port of said rear-seat inflation chamber is opened in a directionsubstantially orthogonal to an axial direction of said gas passage, andits front-side peripheral edge is disposed to be higher than itsrear-side peripheral edge.
 2. An air bag in use for a head protectionair bag device according to claim 1, wherein said front-side peripheraledge is higher than said rear-side peripheral edge by a dimension of 20mm.
 3. An air bag in use for a head protection air bag device accordingto claim 1, wherein a height dimension of said front-side peripheraledge from said rear-side peripheral edge is in a range of 15 to 40% of aheight dimension of said gas passage.
 4. An air bag in use for a headprotection air bag device according to claim 1, further comprising apartitioning part parting said gas passage from said rear-seat inflationchamber to thereby define said inflow port of said rear-seat inflationchamber, said partitioning part comprising a beginning part and a linearpart linearly slanting downward from said beginning part in a frontwarddirection and said rear-side peripheral edge of said inflow port of saidrear-seat inflation chamber is positioned at a fore end of said linearpart.
 5. An air bag in use for a head protection air bag deviceaccording to claim 1, further comprising a partitioning part partingsaid gas passage from said rear-seat inflation chamber to thereby definesaid inflow port of said rear-seat inflation chamber, said partitioningpart comprising a beginning part and a linear part linearly slantingdownward from said beginning part in a rearward direction and saidfront-side peripheral edge of said inflow port of said rear-seatinflation chamber is positioned at a fore end of said linear part.
 6. Anair bag in use for a head protection air bag device according to claim1, further comprising a guide formed on an upper peripheral wall of saidgas passage located above an inflow port of said front-seat inflationchamber such that the upper peripheral part is gently projected downwardin a frontward direction.
 7. An air bag in use for a head protection airbag device according to claim 6, wherein a projection quantity between alower end of said guide and said upper peripheral wall of said gaspassage is set at 30 mm.
 8. An air bag in use for a head protection airbag device according to claim 6, wherein a projection quantity between alower end of said guide and said upper peripheral wall of said gaspassage is in a range of 20 to 50% of a height dimension of said gaspassage.
 9. An air bag in use for a head protection air bag device inwhich said air bag, while being folded, is stored in an upper fringe ofopenings on a cabin-inside side of a vehicle, said air bag comprising: agas inflow part for flowing inflation gas; a gas passage extendingforward from said gas inflow part; a front-seat inflation chamberlocated at a position near a side of a front seat for receiving theinflation gas; and a rear-seat inflation chamber located at a positionnear a sides of a rear seat for receiving the inflation gas, said front-and rear-seat inflation chambers being disposed below said gas passagethrough respective inflow ports formed in upper parts of said front- andrear-seat inflation chambers to allow the inflation gas to flow intosaid front- and rear-seat inflation chambers; and a guide formed on anupper peripheral wall of said gas passage located above an inflow portof said front-seat inflation chamber such that the upper peripheral partis gently projected downward in a frontward direction.
 10. An air bag inuse for a head protection air bag device according to claim 9, wherein aprojection quantity between a lower end of said guide and said upperperipheral wall of said gas passage is set at 30 mm.
 11. An air bag inuse for a head protection air bag device according to claim 9, wherein aprojection quantity between a lower end of said guide and said upperperipheral wall of said gas passage is in a range of 20 to 50% of aheight dimension of said gas passage.
 12. An air bag in use for a headprotection air bag device according to claim 9, wherein said inflow portof said rear-seat inflation chamber is opened in a directionsubstantially orthogonal to an axial direction of said gas passage, andits front-side peripheral edge is disposed to be higher than itsrear-side peripheral edge.
 13. An air bag in use for a head protectionair bag device according to claim 12, wherein said front-side peripheraledge of said rear-seat inflation chamber is higher than said rear-sideperipheral edge by a dimension of 20 mm.
 14. An air bag in use for ahead protection air bag device according to claim 12, wherein a heightdimension of said front-side peripheral edge from said rear-sideperipheral edge is in a range of 15 to 40% of a height dimension of saidgas passage.
 15. An air bag in use for a head protection air bag deviceaccording to claim 12, further comprising a partitioning part partingsaid gas passage from said rear-seat inflation chamber to thereby definesaid inflow port of said rear-seat inflation chamber, said partitioningpart comprising a beginning part and a linear part linearly slantingdownward from said beginning part in a frontward direction and saidrear-side peripheral edge of said inflow port of said rear-seatinflation chamber is positioned at a fore end of said linear part. 16.An air bag in use for a head protection air bag device according toclaim 12, further comprising a partitioning part parting said gaspassage from said rear-seat inflation chamber to thereby define saidinflow port of said rear-seat inflation chamber, said partitioning partcomprising a beginning part and a linear part linearly slanting downwardfrom said beginning part in a rearward direction and said front-sideperipheral edge of said inflow port of said rear-seat inflation chamberis positioned at a fore end of said linear part.